DEAR DR. DONOHUE: My doctor insisted I have a colonoscopy to look for cancer. I had one, and I don’t have cancer, but I do have diverticulosis. I don’t know what to do about it. The doctor never mentioned any special diet. What is the appropriate one? – R.V.

ANSWER: You share diverticulosis with a very large number of people. More than half of those older than 60 have it. A brief explanation will make it less formidable.

The colon is a tube with muscular walls and an inner lining that draws water from undigested food. A diverticulum is a pea-sized bulge of the inner lining through the muscular wall. It forms a tiny sac on the colon’s outer surface. Most often diverticula don’t cause trouble and don’t cause pain.

If the neck of a diverticulum becomes blocked with a piece of rock-hard stool, the diverticulum becomes inflamed, swells and causes great pain and, sometimes, rectal bleeding. That’s diverticulitis, and it happens to only a small percentage of people with diverticulosis.

The diet for prevention of the formation of more diverticula and for the prevention of diverticulitis is a high-fiber diet. The colon must generate great force to move dried-out food through its entire length. That force, in turn, causes the colon lining to bulge through its muscular wall. Keeping fecal material soft effectively stops diverticula formation and keeps already-formed diverticula from becoming plugged.

You know you’re getting enough fiber – around 25 grams a day – when your stools are soft. Fruits, vegetables and whole grains are high-fiber foods. There are many commercial high-fiber cereals that make it easy to reach the 25-gram goal. Bran, obtainable in health-food stores, and psyllium, found in drugstores, are other fiber sources. At one time, doctors warned their diverticulosis patients to stay away from nuts, popcorn, corn and seeds to prevent obstructing a diverticulum’s neck. In some cases, that is still necessary, and your doctor is the one to advise you about such restrictions. For many others, such restrictions have been lifted.

The diverticulosis booklet presents this subject in greater depth. To order a copy, write: Dr. Donohue – No. 502, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6.75 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: My 20-year-old son has stopped brushing his teeth. He thinks it isn’t necessary anymore because his teeth were sealed by a dentist. He also has a tongue stud and lip piercing. I think this is very dangerous. His gums are already red and swollen, and his teeth look terrible. Please help. – C.E.

ANSWER: Sealing protects teeth, but your son is delusional if he thinks he can eliminate brushing his teeth because they were sealed. Everyone has to brush at least twice a day to maintain dental health as well as gum and tongue health. In addition, people should floss twice a day.

His tongue stud and lip ring, while undoubtedly adding to his magnetic attractiveness, are additional dangers to his teeth.

If you can see swollen gums and discolored teeth now, before much longer your son risks the prospects of not having his own teeth.

DEAR DR. DONOHUE: Will you write about low blood pressure? My daughter has it and is very fatigued. She is a very active dance teacher. Her doctor is not concerned. – P.R.

ANSWER: Blood pressure lower than 120/80 is healthy and lessens the risk of heart and artery disease. Unless low pressure makes a person weak, dizzy or prone to abnormal heartbeats, then such pressure lengthens life.

If the systolic pressure (the first number) is lower than 90, symptoms often appear, and then a search for the cause of such low pressure has to be initiated. One such cause is nonfunctioning adrenal glands.

Your daughter is an active dance teacher, an occupation that demands great physical exertion. If she’s able to manage such a demanding job, it’s not likely that her low blood pressure is causing her fatigue. Perhaps she’s not getting enough rest.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.